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ESSENTIALS OF CHEMICAL PHYSIOLOGY 



centre of the slide C, a cover glass is gently laid on (so as to touch the drop 

 which thus forms a layer J millimetre thick between the slide and cover 

 glass), and pressed down by two brass springs. In a few minutes the 

 corpuscles have sunk to the bottom of the layer of fluid, and rest on the 

 squares. The number on ten squares is then counted, and this multiplied 

 by 10,000 gives the number in a cubic millimetre of blood. The average 

 number of red corpuscles in each square ought therefore in normal human 

 blood to be 45-50. 



Oliver's Haemacytometer. — The following method devised by Dr. George 

 OUver is a ready way of determining the total number of corpuscles. It is,, 

 however, not possible to determine the relative proportion of red and white 

 corpuscles by this means. 



Fi<i. C5.— Olivei's hicmnoytometer. 



